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Date:      Sun, 21 Aug 2005 19:17:06 +0200
From:      "Poul-Henning Kamp" <phk@phk.freebsd.dk>
To:        Alexander Leidinger <Alexander@Leidinger.net>
Cc:        arch@freebsd.org, Robert Watson <rwatson@freebsd.org>
Subject:   Re: [CFR] reflect resolv.conf update to running application 
Message-ID:  <58449.1124644626@phk.freebsd.dk>
In-Reply-To: Your message of "Sun, 21 Aug 2005 11:54:54 %2B0200." <20050821115454.55441a64@Magellan.Leidinger.net> 

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In message <20050821115454.55441a64@Magellan.Leidinger.net>, Alexander Leidinger writes:
>On Sun, 21 Aug 2005 00:37:56 +0100 (BST)
>Robert Watson <rwatson@freebsd.org> wrote:
>
>> (2) By reading the configuration file more frequently and more quickly
>>      after a change, we increase the chances of a race condition in which
>>      the resolve reads a partially written resolv.conf file during an
>>      update.  Does this happen in practice?  I've always been very leery of
>>      re-reading configuration files automatically based on a time-stamp, as
>>      updates to files are not atomic at all.
>
>Can kqueue be used instead of polling?

Programs writing resolv.conf should just this the right way:

	1. Write new contents to temorary file.
	2. Rename temporary file to resolv.conf.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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